The present invention broadly relates to the regulation of apparatus and, more specifically, pertains to a new and improved method and device for regulating an apparatus or group of apparatuses and to an apparatus having a regulating device.
The apparatus to be regulated can, in particular be arranged to process fabric edges or selvedges and can, for instance, be an electrothermal shear.
Fabric edges or selvedges are in many cases and independently of the weaving process severed or cut off in weaving. The newly formed fabric edge must be bonded.
In woven fabrics which comprise synthetic fiber components, the fabric edges or selvedges are often severed by means of a thermal or heated shear which welds or fuses the newly formed fabric edges during the severing process. In fabrics without a substantial synthetic fiber content, special measures must be taken and special devices employed in order to bond the fabric edges.
However, an exact control of the operation of this processing device in relation to the materials employed in the woven fabric is required for both groups.
In heretofore known devices, especially in known thermal shears, this is not the case.
For example, one known thermal shear comprises a heated rod containing a potentiometer coupled to the rod which is pivotable in a joint or hinge and is journaled to swing or pivot in a direction extending substantially transverse to the plane of the fabric length. This known thermal shear is pressed against the initial or forward edge of a fabric length by means of a spring. In the nearly vertical idle position, the potentiometer feeds a current into the rod which prevents the rod from heating too strongly or from heating at all. As the rod is deflected by the traveling fabric length, the potentiometer feeds a current into the heated rod enabling the rod to sever the fabrics.
This thermal shear has the disadvantage that the heated rod continues to melt the fabric with its residual heat after the cloth of fabric length has ceased to move and the cutting or severing current has been switched off. Since the fabric length no longer moves, damage to the fabric occurs in the region of the idle position of the only slowly cooling rod.
Another electrothermal cutting apparatus is known from the German Pat. No. 3,140,560 and comprises a circuit arrangement for regulating the supply of current during the operating interval and during the idle interval. The circuit arrangement automatically sets a higher current supply at the beginning of the operating interval and switches it off again at the end of the operating interval. The circuit arrangement also comprises circuitry operating according to the phase shift control method and having adjustable delay circuits and a switching device actuated by the drive of the machine being regulated. The time constant of the first delay device depends upon the position of a closure contact controlled by the processing machine. Both delay circuits conjointly with a power control stage effect a phase shift control whose firing or triggering angle is determined by the two delay circuits.
The magnitude of the firing or triggering angle determines the onset and the duration of the current flow through the power control stage and through the cutting or severing device. The current flow or flux can be adapted to the type and thickness of the fabric to be severed as well as to the operating and idle intervals. A substantial disadvantage of this circuit arrangement is the very slow temperature rise at the shear or shears when switching from the idle interval to the operating interval. For rapidly operating machines this temperature rise occurs too slowly, which leads to fabric waste or scrap.